Subject: Re: IIc Mouse not moving vertically From: dempson@actrix.gen.nz (David Empson) Date: Wed, Oct 7, 1998 86 Message-id: <1dgk9ij.zadgpibo5jtrN@dempson.actrix.gen.nz> Myles Fudge wrote: > Lately my IIc mouse have not being moving vertically... only horizontally. > The mouse pointer moves across the top of the screen okay, but it is stuck > on that line. I have been testing my mouse with ProTERM v3.0. And this > is the mouse I have had for years. I notice that the mouse pointer > character flickers if I move the mouse vertically, but the pointer stays > on the top line of the screen. The flicker is probably due to the software detecting a very small horizontal movement while you are trying to move the mouse vertically. > I have tried two different mice and I assume now that the problem is with > the IIc and not the mice. Does anyone know of a common problem that > prevents a IIc mouse from not moving vertically? I'm not aware of any common problem that might cause this, but it is certainly possible that there could be a motherboard fault that is preventing the vertical movement signals from being detected. Two of the pins on the connector provide a pulse train to the IIc as the mouse moves vertically (pins 8 and 9). One pulse is generated for each unit of movement, and the phase relationship between the signals determines the direction. The IIc gets interrupted for each unit of movement (lots of overhead!), and the main CPU is responsible for updating the mouse position data accordingly. The critical one is pin 9 (YMOVE): each rising edge on this signal causes a vertical movement interrupt. A fault could be due to a corroded pin or track. If you want to investigate further, can take apart your IIc and have a continuity tester, check that the signal from pin 9 of the mouse/joystick port is connected to pin 10 of the 40-pin IOU chip. -- David Empson dempson@actrix.gen.nz Snail mail: P.O. Box 27-103, Wellington, New Zealand